1. Field of the Invention
The present invention relates to an apparatus for manufacturing semiconductor wafers and, more particularly, to an apparatus for etching semiconductor wafers.
2. Description of Related Art
Methods referred to as "dry etching" and "wet etching" are known as methods for etching a silicon oxide film on a semiconductor wafer. Dry etching is a method wherein a semiconductor wafer is etched by exposing it in an atmosphere of an etching gas such as HF or HF/H.sub.2 O. On the other hand, wet etching is a method wherein a semiconductor wafer is etched by immersing it in, for example, a water solution of HF for a predetermined period of time. Recently, due to increasing demand for highly integrated devices, dry etching that provides higher etching efficiency has been the mainstream art.
However, dry etching also has a problem in that by-products of etching remain on the surface of a wafer. The dry-wet-dray etching system has been conceived taking such a situation into consideration. The dry-wet-dray etching is a method in which the surface of a wafer is sufficiently cleaned by pure water or the like after dry etching as described above and is dried by evaporating moisture thereon. This method eliminates the possibility of contamination by by-products after dry etching.
However, in order to implement the dry-wet-dry scheme, a dry etching apparatus, a cleansing apparatus, and drying apparatus must be prepared separately, which has resulted in a problem associated with the space for such apparatuses and a problem of contamination during transportation of wafers between those apparatuses.
Conventional apparatuses had another problem in that magnetic seals which produce less dust can not be used as sealing members at the step of dry-etching for reasons with respect to corrosion resistance.
While the spin drying system in which a wafer is rotated to scatter water droplets with a centrifugal force is generally utilized as drying method at the step of drying, there has been a possibility of contamination of a wafer due to dust produced by friction at rotating portions during the step.
It is therefore an object of the present invention to provide an integrated semiconductor processing apparatus in which the above-described dry-wet-dry etching scheme can be easily implement at a time.
It is another object of the present invention to provide a sealing mechanism which prevents dust from rotating portions or from the outside of a reaction chamber from contaminating a semiconductor wafer during executing all steps of dry-wet-dry etching.